Skip to main content

Remaining stretch of I-485 will feature three unique types of interchanges

The remaining 5.4 miles of I-485 currently under construction in Mecklenburg County will feature three unique interchanges.  All three are in use elsewhere within the country, but would be the first ones built in the Tar Heel State.

At two of the interchanges, the new designs are considered upgrades (in traffic flow and cost savings) versus what had originally been planned.

The interchange design names are Split Diamond, Diverging Diamond, and Turbine.

Heading East from the current terminus at NC 115, the three new interchange designs run as follows:

The Split Diamond interchange will be located at Prosperity Church Road.  This interchange will consist of two access roads and six roundabouts.

Split Diamond Interchange with Prosperity Church Road (NCDOT)
The Diverging Diamond Interchange (DDI), first used in Missouri, is starting to catch interest in North Carolina.  The interchange design, actually reverses the lanes of traffic on the surface/cross street.  This will be located at the Mallard Creek Road exit on I-485.

This design replaces a planned Single Point Urban Interchange (SPUI) for 485 and Mallard Creek.


We covered a Diverging Diamond Interchange back in October when NCDOT announced it is considering the design on NC 133 where it meets the US 74/76 freeway in Leland.  These two intersections, along with two more on nearby Interstate 85 at NC 73 and Poplar Tent Road, are some of seven prospective locations for this new style of interchange.

Finally, the Turbine - an interchange that has all left turn movements circling around a central bridge in a clockwise direction, creating a seamless movement between the two highways.  This replaces the previously planned four-level stack interchange.  (Similar in design to where I-77 and 485 meet in Southern Mecklenburg County.)

The new "Turbine" interchange at 85/485.  (NCDOT)      
According to NCDOT, this type of interchange will cost less to build and maintain, take up less space, and allow for less interruptions to existing I-85 traffic during construction.


Story Links:
Last Outerbelt juntions to display unique functions ---Charlotte Observer
I-485 Charlotte Outer Loop ---NCDOT

Comments

Froggie said…
NCDOT apparently doesn't see it as such, but I-40/Exit 195 (at NC 109) in Winston-Salem, is very much a split-diamond.
Anonymous said…
Should that be counterclockwise, or am I missing something? (Maybe clockwise in countries that drive on the left...)
Reminds me of my Alexandria Orb proposal:

http://wwwtripwithinthebeltway.blogspot.com/2007/02/alexandria-orb-page-one-news-december.html

http://wwwtripwithinthebeltway.blogspot.com/search/label/Alexandria%20Orb

Popular posts from this blog

Horace Wilkinson Bridge (Baton Rouge, LA)

Standing tall across from downtown Baton Rouge, the Horace Wilkinson Bridge carries Interstate 10 across the lower Mississippi River between West Baton Rouge and East Baton Rouge Parishes. Unusually, the bridge is actually named for three separate people; three generations of Horace Wilkinsons who served in the Louisiana State Legislature over a combined period of 54 years. Constructed in the 1960s and opened to traffic in 1968, this is one of the largest steel bridges on the lower Mississippi. It’s also the tallest bridge across the Mississippi, with its roadway reaching 175 ft at the center span. Baton Rouge is the northernmost city on the river where deep-water, ocean-going vessels can operate. As a result, this bridge is the northernmost bridge on the river of truly gigantic proportions. Altogether, the bridge is nearly 2 ½ miles long and its massive truss superstructure is 4,550 ft long with a center main truss span of 1,235 ft. The Horace Wilkinson Bridge is one of the largest

Sunshine Bridge (Donaldsonville, LA)

Located about halfway between Baton Rouge and New Orleans in southern Louisiana, the Sunshine Bridge spans the lower Mississippi River near the city of Donaldsonville as part of the longer Louisiana Highway 70 corridor, which connects Interstate 10 and Airline Highway (US 61) with US 90 in Morgan City. In the years following World War II, the only bridges across the lower Mississippi River in Louisiana were located in the area of the state’s two largest cities – Baton Rouge and New Orleans. Postwar agricultural and industrial development along the river in this region led to the planning of a series of infrastructure projects in southern Louisiana that were aimed at spurring this development and modernization of the Delta region. One of these projects was known as the Acadian Thruway and was developed in the 1950s as a toll road intended to connect greater New Orleans with Lafayette and points west while providing a high-speed bypass of the Baton Rouge metro area. The Thruway, which

Natchez-Vidalia Bridge (Natchez, MS)

  Located about halfway between Baton Rouge and Vicksburg near the city of Natchez, the Natchez-Vidalia Bridge crosses the lower Mississippi River between southwest Mississippi and northeastern Louisiana at the city of Vidalia. This river crossing is a dual span, which creates an interesting visual effect that is atypical on the Mississippi River in general. Construction on the original bridge took place in the late 1930s in conjunction with a much larger parallel effort by the U.S. Army Corps of Engineers to strengthen the area’s flood protection and levee system along the Mississippi River. One of the more ambitious aspects of this plan was to relocate the city of Vidalia to a location of higher ground about one mile downriver from the original settlement. The redirection of the river through the Natchez Gorge (which necessitated the relocation of the town) and the reconstruction of the river’s levee system in the area were undertaken in the aftermath of the Great Flood of 1927, wh